mirror of
https://github.com/FEX-Emu/linux.git
synced 2024-12-25 02:48:21 +00:00
xen-blkfront: add BLKIF_OP_DISCARD and discard request struct
Now we use BLKIF_OP_DISCARD and add blkif_request_discard to blkif_request union, the patch is taken from Owen Smith and Konrad, Thanks Signed-off-by: Owen Smith <owen.smith@citrix.com> Signed-off-by: Li Dongyang <lidongyang@novell.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
parent
322a8b0340
commit
32a8d26cc9
@ -57,6 +57,36 @@ typedef uint64_t blkif_sector_t;
|
||||
* "feature-flush-cache" node!
|
||||
*/
|
||||
#define BLKIF_OP_FLUSH_DISKCACHE 3
|
||||
|
||||
/*
|
||||
* Recognised only if "feature-discard" is present in backend xenbus info.
|
||||
* The "feature-discard" node contains a boolean indicating whether trim
|
||||
* (ATA) or unmap (SCSI) - conviently called discard requests are likely
|
||||
* to succeed or fail. Either way, a discard request
|
||||
* may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
|
||||
* the underlying block-device hardware. The boolean simply indicates whether
|
||||
* or not it is worthwhile for the frontend to attempt discard requests.
|
||||
* If a backend does not recognise BLKIF_OP_DISCARD, it should *not*
|
||||
* create the "feature-discard" node!
|
||||
*
|
||||
* Discard operation is a request for the underlying block device to mark
|
||||
* extents to be erased. However, discard does not guarantee that the blocks
|
||||
* will be erased from the device - it is just a hint to the device
|
||||
* controller that these blocks are no longer in use. What the device
|
||||
* controller does with that information is left to the controller.
|
||||
* Discard operations are passed with sector_number as the
|
||||
* sector index to begin discard operations at and nr_sectors as the number of
|
||||
* sectors to be discarded. The specified sectors should be discarded if the
|
||||
* underlying block device supports trim (ATA) or unmap (SCSI) operations,
|
||||
* or a BLKIF_RSP_EOPNOTSUPP should be returned.
|
||||
* More information about trim/unmap operations at:
|
||||
* http://t13.org/Documents/UploadedDocuments/docs2008/
|
||||
* e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
|
||||
* http://www.seagate.com/staticfiles/support/disc/manuals/
|
||||
* Interface%20manuals/100293068c.pdf
|
||||
*/
|
||||
#define BLKIF_OP_DISCARD 5
|
||||
|
||||
/*
|
||||
* Maximum scatter/gather segments per request.
|
||||
* This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
|
||||
@ -74,6 +104,11 @@ struct blkif_request_rw {
|
||||
} seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
|
||||
};
|
||||
|
||||
struct blkif_request_discard {
|
||||
blkif_sector_t sector_number;
|
||||
uint64_t nr_sectors;
|
||||
};
|
||||
|
||||
struct blkif_request {
|
||||
uint8_t operation; /* BLKIF_OP_??? */
|
||||
uint8_t nr_segments; /* number of segments */
|
||||
@ -81,6 +116,7 @@ struct blkif_request {
|
||||
uint64_t id; /* private guest value, echoed in resp */
|
||||
union {
|
||||
struct blkif_request_rw rw;
|
||||
struct blkif_request_discard discard;
|
||||
} u;
|
||||
};
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user